The present invention relates to a position control apparatus and position control method for a cargo carrying apparatus on an industrial vehicle, and, more particularly, to a technique for automatically positioning a cargo carrying apparatus on an industrial vehicle with respect to a cargo handling target based on image data obtained by picking up an image of the cargo handling target.
A forklift, one type of industrial vehicles, has a multi-level mast, a carriage liftable up and down along the mast, and a cargo carrying apparatus attached to the carriage, or forks. In general, in case where a cargo carrying work is performed with a forklift, a load is placed on a pallet and the load-deposited pallet is carried by the forks. In case of taking out a pallet on a rack at a high place (e.g., 3 to 6 meters) or in case of placing a pallet on that rack, a driver operates a lift lever to lift the forks up along the mast and protract the mast. Then, the positions of the forks are adjusted in such a way that the forks are positioned with respect to the pallet or the rack as a cargo handling target.
At this time, the driver must operate the lift lever in such a way as to adjust the positions of the forks while looking up at the high place. However, such a positioning work is difficult and even a skilled person needs time for the work.
U.S. Pat. No. 5,586,620 discloses an apparatus for aiding a work of positioning forks at a high place. In this apparatus, a camera is mounted to a carriage for supporting the forks and a video image picked up by the camera is shown to a driver in a driver's seat via a display device. Because the driver can see the situation in front of the forks through the display device, the driver can do a fork positioning work at a high place relatively easily and accurately.
However, the apparatus merely performs visual aiding. Specifically, the apparatus merely uses a camera for picking up an image of an area at a high place, which is difficult to see from the driver's seat, and shows the image to the driver. The driver needs to do a work of positioning the forks with respect to a cargo handling target through a manual operation and a considerable burden of the cargo carrying work is still imposed on the driver.